For the CIM part of the paper, workings are compulsory in order to gain all the marks. For the angle calculating question on the front page, I got one out of two marks for getting the right answer but not writing the steps.

There is one question that asks to find the area of a triangle, given two sides and the angle in between. When using the formula of Area = 0.5 · a · b · sin(C), I wrote the formula then calculated the answer directly, skipping the step of substituting the values of a, b and C in. And I got … 0 out of the 2 marks. So the step of substituting values into a formula should always be written.

It is also no ok, surprisingly (to me), to skip steps when solving equations. When I got to the step 16k2 - 112k + 192 < 0, the next step I wrote was 3 < k < 4, skipping the step of factorising the quadratic expression, I got a mark off. It is necessary to simplify the left side of < into k2 - 7k + 12 then factorise it: (k + 3)(k - 4).

After these marks lost due to skipping workings, here are my silly mistakes due to misreading the questions or not reading the key instructions in the question.

No.1

The graph below shows the relationship between log10x and log10y. Find y in terms of x.

So I went finding the formula assuming that the graph was plotted with y against x … and lost half of the marks.

No.2

The function f is defined by f(x) = 63/(4x-1) for 1 ≤ x ≤ 16.
The graph y = f(x) is shown below.
Find the range of f.

So here through the graph I found that the graph seems to have a horizontal asymptote of y = 0 and therefore I wrote – range: {f|f∈ℝ, f>0}… And obviously I got 0 mark for writing this. I didn’t use anything given in the question other than the graph. The right way to find the range should be substituting the highest and lowest value of the domain into the function to find out the highest and lowest values of the range.

So the above mistakes takes 9 marks away and I was barely over the mark required for a “7”. It is too bad that I don’t get a second chance for doing a paper for the report in October, but hopefully when it comes to the mocks in November, I would be able to avoid these mistakes.

Up Next:

#### IGCSE Geo Revision – Tourism

IGCSE Geo Revision – Tourism